/Engine/Source/Runtime/RenderCore/Public/RendererInterface.h
void RequestVirtualTextureTilesForRegion ( [IAllocatedVirtualTexture](API\Runtime\RenderCore\IAllocatedVirtualTexture) * AllocatedVT, const FVector2D & InScreenSpaceSize, const FVector2D & InViewportPosition, const FVector2D & InViewportSize, const FVector2D & InUV0, const FVector2D & InUV1, int32 InMipLevel )